A lithography technique leads development of miniaturization of semiconductor devices. The lithography technique is the only extremely important process that generates a pattern, in semiconductor manufacturing processes. Recently, as LSIs have been highly integrated, a circuit pattern linewidth required for the semiconductor devices has been miniaturized every year. A high-precision original pattern (also referred to as a reticle or a mask) is required in order to form a desired circuit pattern to the semiconductor devices. An electron beam (EB) lithography technique has essentially excellent resolution. The electron beam lithography technique is used for manufacturing high-precision original patterns.
FIG. 11 is a schematic view for describing operation of a variable-shaped electron beam lithography apparatus in the related art. The variable-shaped electron beam lithography apparatus is an example of variable-shaped charged particle beam lithography apparatuses. The variable-shaped electron beam lithography apparatus operates as follows: A quadrilateral opening 411 for forming an electron beam 330 is formed on a first aperture plate 410. A variable-shaped opening 421 is formed on a second aperture plate 420. The variable-shaped opening 421 forms the electron beam 330 that has passed through the opening 411 of the first aperture plate 410, into a desired quadrilateral shape. The electron beam 330 that has been irradiated from a charged particle beam source 430 and has passed through the opening 411 of the first aperture plate 410 is deflected by a deflector. Then, the electron beam 330 passes through a part of the variable-shaped opening 421 of the second aperture plate 420. After that, a target object 340 mounted on a stage continuously movable in a predetermined direction (for example, in an X direction), is irradiated with the electron beam 330. That is, a quadrilateral shape capable of passing through both the opening 411 of the first aperture plate 410 and the variable-shaped opening 421 of the second aperture plate 420, is written in a pattern writing region of the target object 340 mounted on the stage continuously movable in the X direction. A method for forming an arbitrary shape by causing the electron beam 330 to pass through both the opening 411 of the first aperture plate 410 and the variable-shaped opening 421 of the second aperture plate 420 is referred to as a variable-shaped method (VSB method).
The number of shots of the electron beam, required for forming a mask pattern, has increased at an accelerated rate in association with the development of a photolithography technique by introducing the shorter wavelength of Extreme Ultra Violet (EUV) light. Meanwhile, in order to secure linewidth precision necessary for miniaturization, making a resist have low sensitivity and increasing a dose achieve reduction of shot noise and edge roughness of a pattern. In this manner, the number of shots and the dose have boundlessly continued to increase. Thus, pattern writing time boundlessly increases. Therefore, it has been examined that increasing current density achieves reduction in the pattern writing time.
However, when a further high-density electron beam irradiates an amount of irradiation energy that has increased, in a short time, the temperature of a substrate increases and the sensitivity of the resist varies. That is, there is a problem that a phenomenon referred to resist heating occurs.
JP 2013-243285 A describes a lithography apparatus including a number operation unit, a representative temperature calculator, and a dose modulator. In order to inhibit a size variation of a pattern due to resist heating while a correction calculating speed is caused not to be late for a pattern writing speed, with average pattern writing time of a TF (under-subfield), average calculating time for calculating a temperature rise amount caused by a heat transfer of each of a plurality of other TFs written before the TF, and parallelism of a calculator, the number operation unit operates the number of the plurality of other TFs, written before the TF, used when a temperature rise amount for causing calculating time for calculating an temperature rise amount of all TFs to be written not to exceed pattern writing time of all the TFs, is calculated. The representative temperature calculator calculates a representative temperature of the TF based on a heat transfer from the number of the plurality of other TFs with respect to each TF. The dose modulator inputs a dose to be irradiated to the TF and modulates the dose to be irradiated to the TF with the representative temperature of the TF.